The structures of several glycopeptides obtained from cuttlefish skin collagen by Pronase-P digestion were established and compared with those of three known glycopeptides from vertebrates. The results indicate that around the carbohydrate-carrying hydroxylysine residue there exists a common amino acid sequence, Gly-X-Hyl-Gly-Y-Arg, which seems to act as a recognition sign during the glycosylation processes of collagen molecules.